Hmm... religious zealots, eh? Let's look at this: http://www4.law.cornell.edu/uscode/html/uscode18/usc_sec_18_00002257----000-.html
So basically he had to shut down the site because he did not keep records of all the women who submitted photos. The first reaction would be to request that all photo submissions come with a record, but that is not very logical due to this being the internet.
However, if you look here:
(h) As used in this section
(1) the term actual sexually explicit conduct means actual but not simulated conduct as defined in subparagraphs (A) through (D) of paragraph (2) of section 2256 of this title;
Then here:
Except as provided in subparagraph (B), sexually explicit conduct means actual or simulated
(i) sexual intercourse, including genital-genital, oral-genital, anal-genital, or oral-anal, whether between persons of the same or opposite sex;
(ii) bestiality;
(iii) masturbation;
(iv) sadistic or masochistic abuse; or
(v) lascivious exhibition of the genitals or pubic area of any person;
Now, if the website was simply rating the breasts of women (without any of the above actions), it should be allowed, by my understanding. So all he needs to do is refuse to post photographs of sex or masturbation (I don't think S&M or bestiality would be too much of a problem) and he's set.